The proposed investigation is a study of mechanism of carcinogenesis in the urinary bladder after administration of chemical carcinogens. The specific aims are: 1. To determine if dietary indole or excess tryptophan has an enhancing effect on the bladder tumorigenesis by 2-acetyl-aminofluorene or N-dibutylnitrosamine in hamsters when the carcinogens are given at several very low levels. 2. To determine if sulfate ester formation of N-hydroxy-2- acetylaminofluorene is an important step in the bladder tumorigenesis, and what is the role of indole in this regard. 3. To determine if dietary indole enhances the uptake of N-hydroxy-2-acetyl-aminofluorene to the bladder mucosa. 4. To determine if a dietary secondary amine (N- dibutylamine) can induce bladder tumors in hamsters when combined with sodium nitrite added to the drinking water. These objectives require the use of an animal room which can comply with the NIH and USDA regulations for the maintenance of experimental animals for cancer research. Also, the University to comply with the regulations, we must keep all breeder colon in the University animal housing area.